JP2020197554A - Image display device - Google Patents

Abstract

To provide an image display device in which, when the light quantity is adjusted in accordance with input image data, the discomfort of a display image in scene change is reduced while the driving frequency of a driving motor is suppressed.SOLUTION: An image display device includes a scene luminance detection unit that detects scene luminance information expressing the brightness of a scene including a plurality of image frames, a light adjustment unit that adjusts the light quantity of a light source by controlling a light-blocking member that blocks the light quantity of the light source, and a light quantity control unit that controls the light adjustment quantity of the light adjustment unit. The scene luminance information that is detected by the scene luminance detection unit is updated less frequently than the change of a signal level of an image signal. The light quantity control unit controls the light adjustment quantity on the basis of the scene luminance information detected by the scene luminance detection unit.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image display device, and more particularly to a projection type display device such as a projector.

Conventionally, with respect to a projection type display device, a technique of adjusting the amount of light according to input image data in order to improve display contrast has been proposed.

Patent Document 1 discloses a technique for adjusting the amount of light by controlling the amount of light of an arc tube as a light source and an optical diaphragm for narrowing down the light emitted from the light source according to input image data.

Further, in Patent Document 2, a variable diaphragm that narrows down the amount of light according to input image data is controlled, and whether the image is a moving image or a still image is discriminated, and the diaphragm amount of the variable diaphragm is determined according to the discrimination result. The technique for adjusting is disclosed.

Japanese Patent No. 4238765 Japanese Patent No. 5512484

In the prior art disclosed in Patent Document 1, luminance information is detected for each frame of input image data, and a drive motor (stepping motor) for driving an optical diaphragm is controlled based on the detected luminance information. When the input image data is a moving image having a large variation in luminance, the change in the luminance information to be detected increases. If the optical diaphragm is driven quickly in an attempt to follow the detected luminance information as quickly as possible, the drive motor will be driven more frequently. However, a drive motor such as a stepping motor has a limited life, and it is necessary to reduce the drive frequency so as not to exceed the design life of the drive motor. On the contrary, if the drive motor is slowly moved so as to reduce the drive frequency of the drive motor, for example, when the input image changes from a dark scene to a bright scene, the dimming of the amount of light by the optical diaphragm is delayed, so that the display image There is a problem that a feeling of strangeness occurs.

Further, as in the prior art described in Patent Document 2, when the input image data is a still image, the brightness displayed in the still image and the moving image is increased by increasing the aperture amount and controlling the darkness as compared with the moving image. There was a problem that it would be different.

Therefore, an object of the present invention is to provide an image display device that reduces the discomfort of the displayed image at the time of a scene change while suppressing the number of times the drive motor is driven when dimming the amount of light according to the input image data. And.

In order to achieve the above object, the image display device according to the present invention is
An image display device that controls the amount of light according to the brightness of the image signal.
A scene brightness detector that detects scene brightness information that indicates the brightness of a scene consisting of multiple image frames,
A dimming unit that dims the amount of light from the light source by controlling a light-shielding member that blocks the amount of light from the light source.
It has a light amount control unit that controls the dimming amount of the dimming unit.
The scene luminance information detected by the scene luminance detection unit is updated less frequently than the change in the signal level of the image signal.
The light amount control unit is characterized in that the dimming amount is controlled based on the scene brightness information detected by the scene brightness detection unit.

According to the image display device according to the present invention, when adjusting the amount of light according to the input image data, it is possible to reduce the discomfort of the displayed image at the time of a scene change while suppressing the number of times the drive motor is driven.

Block diagram showing an example of the image processing apparatus according to the first and second embodiments. Schematic diagram showing the relationship between the detected luminance value and the light intensity control value according to the first and second embodiments. Schematic diagram showing the relationship between the light amount control value and the output light amount according to the first and second embodiments. Schematic diagram showing the relationship between the light intensity control value and the gain value according to the first and second embodiments. Schematic diagram showing the time transition of the frame average brightness according to the first and second embodiments. Schematic diagram showing the time transition of the scene average brightness according to the first and second embodiments. The schematic diagram which shows the time transition of the light amount control value which concerns on Example 1 and Example 2. Schematic diagram showing the time transition of the light source unit according to the first and second embodiments.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

Description of Configuration FIG. 1 is an example of an image processing apparatus according to an embodiment of the present invention.

In FIG. 1, the present embodiment shows an image signal input unit 101, a frame brightness detection unit 102, a scene brightness detection unit 103, a light amount control unit 104, a light source unit 105, a dimming unit 106, a correction amount control unit 107, and an image signal correction. It is composed of a unit 108, a display panel unit 109, a projection lens unit 110, and a screen 111.

The image signal input unit 101 is, for example, an input terminal for an image signal such as HDMI (registered trademark) (High-Definition Multimedia Interface), DVI (Digital Visual Interface), and DisplayPort. The image signal input unit 101 is connected to an image signal output device such as a personal computer or a video player. The image signal input unit 101 receives the image signal output by the image signal output device and the metadata associated with the image signal. The metadata includes, for example, brightness information (average brightness of the scene or maximum brightness of the scene) of a scene composed of a plurality of frames of an image signal. In the case of a bright video scene such as daytime or outdoors, the average scene brightness is a large value, and in the case of a dark video scene such as nighttime or indoors, the average scene brightness is a small value. The scene luminance information is updated when the scene of the image signal is switched. The image signal input unit 101 outputs the received metadata to the scene brightness detection unit 103. Further, the image signal is output to the frame brightness detection unit 102 and the image signal correction unit 108.

The frame luminance detection unit 102 detects the luminance level of the image signal output by the image signal input unit 101. The image signal detection unit 102 detects, for example, the average brightness: APL (Average Picture Level) for each frame of the image signal. The frame average brightness is the average value of the brightness level of the frame of the image signal, and is a large value because the brightness level is high when the image signal is bright, and a small value because the brightness level is low when the image signal is dark. Become. The frame brightness detection unit 102 outputs the detected frame average brightness to the light amount control unit 104. Although the frame luminance detection unit 102 in the present embodiment detects the average value of the luminance levels, the luminance of the image frame may be detected from the histogram showing the distribution of the signal levels.

The scene brightness detection unit 103 detects the scene average brightness indicating the average brightness of the scene from the received metadata, and outputs the detected scene average brightness to the light amount control unit 104.

The light amount control unit 104 determines the light amount control value which is the adjustment amount of the light amount based on the scene average brightness detected by the scene brightness detection unit 103 or the detected brightness value which is the frame average brightness detected by the frame brightness detection unit 102. To do. FIG. 2 is a schematic diagram showing the relationship between the detected luminance value and the light intensity control value. The horizontal axis of FIG. 2 shows the detected luminance value, and the vertical axis shows the light amount control value. In FIG. 2, when the detected luminance value is low, that is, when the image signal level is low and the image is dark, the light intensity control value is a small value. When the detected luminance value is high, that is, when the image signal level is high and the image is bright, the light intensity control value becomes a large value. The light amount control unit 104 outputs the determined light amount control value to the dimming unit 106.

The light source unit 105 includes a lamp such as a high-pressure mercury lamp, a halogen lamp, or a metal halide lamp, an LED (Light Emitting Diode), or a light emitter such as a semiconductor laser, and irradiates the dimming unit 106 with light.

The dimming unit 106 dims the light amount based on the light amount control value output by the light amount control unit 104. The dimming unit 106 is composed of an optical member (light-shielding member) such as a diaphragm or a shutter and a driving unit such as a motor. The dimming unit 106 adjusts the amount of light emitted by the light source unit 105 by driving the motor based on the light amount control value to open / close / move the optical member. The light dimmed by the dimming unit 106 is applied to the display panel unit 109.

FIG. 3 is a schematic diagram showing the relationship between the light amount control value and the output light amount. The horizontal axis of FIG. 3 shows the light amount control value, and the vertical axis shows the light amount output from the dimming unit 106.

In FIG. 3, when the light amount control value is large, the dimming unit 106 controls the light shielding amount to be small and increases the light amount output from the dimming unit 106. When the light amount control value is small, the light shielding amount is largely controlled to reduce the light amount output from the dimming unit 106. In the present embodiment, the dimming unit 106 controls the amount of light emitted by the light source unit 105, but the dimming unit 106 is located between the display panel unit 109 and the projection lens unit 110, or , It may be located inside the projection lens unit 110. Further, when the light source unit 105 can adjust the output light amount, the light amount of the light source unit 105 may be adjusted according to the light amount control value. The correction amount control unit 107 controls the correction amount when the image signal correction unit 108 corrects the image signal. In the present embodiment, the correction amount will be described as a gain value, but the correction amount may be any amount that corrects the level (brightness) of the image signal, for example, a gamma correction amount.

FIG. 4 is a schematic diagram showing the relationship between the light amount control value and the gain value output by the light amount control unit 104. The horizontal axis of FIG. 4 shows the light amount control value, and the vertical axis shows the gain value.

When the light amount control value is small, the light amount is small and dimmed by the dimming unit 106, so that the light amount emitted to the display panel unit 109 is small. Therefore, in FIG. 4, when the light amount control value is small, the gain value, which is the correction amount of the image signal, is increased so as to compensate for the decrease in brightness due to the decrease in the amount of light applied to the display panel unit 109. On the contrary, when the light amount control value is large, the amount of light emitted to the display panel unit 109 is large, so the gain value is reduced. The correction amount control unit 107 outputs a gain value, which is a correction amount, to the image signal correction unit 108.

The image signal correction unit 108 is an image processing block that corrects the level of the image signal. The image signal correction unit 108 corrects the image signal by, for example, multiplying the image signal by the gain value determined by the correction amount control unit 107. The image signal correction unit 108 outputs the corrected image signal to the display panel unit 109.

The display panel unit 109 includes an optical modulation device having a large number of pixels, such as a liquid crystal panel and a DMD (digital mirror device). The display panel unit 109 modulates the illumination light output from the dimming unit 106 according to the level of the image signal corrected by the image signal correction unit 108, and outputs the modulated light to the projection lens unit 110.

The projection lens unit 110 is composed of a projection lens or the like, and projects the light modulated by the display panel unit 109 onto the screen 111, and performs focus control, zoom control, and the like.

-Operation example Hereinafter, an operation example of light intensity control of the image processing apparatus in the present embodiment will be described. As an example of the operation, FIG. 5 shows the time change of the frame average brightness of the image data input to the image signal input unit 101, and FIG. 6 shows the time change of the scene average brightness of the brightness information input to the image signal input unit 101. .. It is assumed that the period from time t0 to time t3 is a dark scene, and the period after time t4 is a bright scene.

At time t0, as shown in FIG. 5, the frame luminance detection unit 102 detects the frame average luminance A1 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t0, which is a dark scene, the light amount control value becomes a low value C1 and is controlled so as to reduce the light amount.

When the next image frame is input, at time t1, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A2 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t1, the average frame brightness increases from A1 to A2, but the light amount control value becomes a low value C1 which is the same as the light amount control value at time t0, and the light amount is kept low and the drive motor of the dimming unit 106 is operated. Do not control.

When the next image frame is input, at time t2, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A1 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t2, the average frame brightness drops from A2 to A1, but the light amount control value becomes a low value C1 which is the same as the light amount control value at time t0, and the light amount is kept lowered and the drive motor of the dimming unit 106 is operated. Do not control.

When the next image frame is input, at time t3, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A2 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t3, the average frame brightness increases from A1 to A2, but the light amount control value becomes a low value C1 which is the same as the light amount control value at time t0, and the light amount is kept low and the drive motor of the dimming unit 106 is operated. Do not control.

When the next image frame is input, at time t4, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A3 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B2. Since the scene average brightness is B2, the light amount control unit 104 determines the light amount control value C2 as shown in FIG. That is, at time t4, the input image changes from a dark scene to a bright scene, and the average frame brightness increases from A2 to A3. Therefore, the light amount control value changes to a high value C2, and the drive motor of the dimming unit 106 is controlled so as to increase the light amount.

When the next image frame is input, at time t5, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A3 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B2. Since the scene average brightness is B2, the light amount control unit 104 determines the light amount control value C2 as shown in FIG. That is, at time t5, the average frame brightness increases from A3 to A4, but the light amount control value becomes a high value C2, which is the same as the light amount control value at time t4, and the drive motor of the dimming unit 106 is operated while keeping the light amount increased. Do not control.

When the next image frame is input, at time t6, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A3 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B2. Since the scene average brightness is B2, the light amount control unit 104 determines the light amount control value C2 as shown in FIG. That is, at time t6, the average frame brightness drops from A4 to A3, but the light amount control value becomes a high value C2, which is the same as the light amount control value at time t4, and the drive motor of the dimming unit 106 is operated while keeping the light amount increased. Do not control.

The transition of the light amount control value is shown in FIG. In FIG. 7, the horizontal axis represents the time and the vertical axis represents the light amount control value determined by the light amount control unit 104. During the period from time t0 to time t3, which is a dark scene, the brightness of the input image data shown in FIG. 5 is a low value between A1 and A2 and changes from frame to frame. On the other hand, the light intensity control value during the period from time t0 to time t3 is constant at C1 as shown in FIG. During the period from time t4 to time t8, which is a bright scene, the brightness of the input image data shown in FIG. 5 is a high value between A3 and A4 and changes for each frame. On the other hand, the light intensity control value during the period from time t4 to time t8 is constant at C2 as shown in FIG. That is, the change in the light amount control value is smaller than the change in the frame average brightness. Therefore, the number of times the drive motor is driven can be suppressed when the amount of light is adjusted according to the input image data. Further, at the time t4 of FIG. 5, the average frame brightness changes greatly and changes from a dark scene to a bright scene, but in FIG. 7, the light amount control value greatly changes (at the time t4) according to the timing of the scene change. Therefore, since the light amount control value is controlled quickly at the time of the scene change, it is possible to reduce the discomfort of the displayed image at the time of the scene change.

If the input image signal is not accompanied by scene brightness information, the scene switching of the input image signal is detected, and the frame average brightness detected from the frame image after the scene is detected is used as the scene average brightness. You may.

Hereinafter, another operation example of the light amount control of the image processing apparatus according to the present embodiment will be described. As an example of the operation, FIG. 5 shows the time change of the frame average brightness of the image data input to the image signal input unit 101, and FIG. 6 shows the time change of the scene average brightness of the brightness information input to the image signal input unit 101. .. It is assumed that the period from time t0 to time t3 is a dark scene, and the period after time t4 is a bright scene.

At time t0, as shown in FIG. 5, the frame luminance detection unit 102 detects the frame average luminance A1 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t0, which is a dark scene, the light amount control value becomes a low value C1 and is controlled so as to reduce the light amount.

When the next image frame is input, at time t1, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A2 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t1, the average frame brightness increases from A1 to A2, but the light amount control value becomes a low value C1 which is the same as the light amount control value at time t0, and the light amount is kept low and the drive motor of the dimming unit 106 is operated. Do not control. Further, the light amount control unit 104 adjusts the light amount of the light source unit 105 so as to compensate for the difference between the frame average brightness and the scene average brightness. At time t1, since the frame average brightness A2 is higher than the scene average brightness B1, the light source unit 105 is controlled to increase the amount of light. FIG. 8 shows the amount of light of the light source unit 105. In FIG. 8, the amount of light is E1 at time t0, but increases to the amount of light E2 at time t1.

When the next image frame is input, at time t2, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A1 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t2, the average frame brightness drops from A2 to A1, but the light amount control value becomes a low value C1 which is the same as the light amount control value at time t0, and the light amount is kept lowered and the drive motor of the dimming unit 106 is operated. Do not control. Further, the light amount control unit 104 adjusts the light amount of the light source unit 105 so as to compensate for the difference between the frame average brightness and the scene average brightness. At time t2, since the frame average brightness A1 and the scene average brightness B1 are equal, the light amount of the light source unit 105 is controlled to be restored. In FIG. 8, the amount of light is E2 at time t1, but the amount of light is E1 at time t2.

When the next image frame is input, at time t3, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A2 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B1. Since the scene average brightness is B1, the light amount control unit 104 determines the light amount control value C1 as shown in FIG. That is, at time t3, the average frame brightness increases from A1 to A2, but the light amount control value becomes a low value C1 which is the same as the light amount control value at time t0, and the light amount is kept low and the drive motor of the dimming unit 106 is operated. Do not control. Further, the light amount control unit 104 adjusts the light amount of the light source unit 105 so as to compensate for the difference between the frame average brightness and the scene average brightness. At time t3, since the frame average brightness A2 is higher than the scene average brightness B1, the light source unit 105 is controlled to increase the amount of light. In FIG. 8, the amount of light E1 is at time t2, but increases to the amount of light E2 at time t3.

When the next image frame is input, at time t4, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A3 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B2. Since the scene average brightness is B2, the light amount control unit 104 determines the light amount control value C2 as shown in FIG. That is, at time t4, the input image changes from a dark scene to a bright scene, and the average frame brightness increases from A2 to A3. Therefore, the light amount control value changes to a high value C2, and the drive motor of the dimming unit 106 is controlled so as to increase the light amount.

When the next image frame is input, at time t5, as shown in FIG. 5, the frame brightness detection unit 102 detects the frame average brightness A3 from the input image data. Further, as shown in FIG. 6, the scene brightness detection unit 103 detects the scene average brightness B2. Since the scene average brightness is B2, the light amount control unit 104 determines the light amount control value C2 as shown in FIG. That is, at time t5, the average frame brightness increases from A3 to A4, but the light amount control value becomes a high value C2, which is the same as the light amount control value at time t4, and the drive motor of the dimming unit 106 is operated while keeping the light amount increased. Do not control. Further, the light amount control unit 104 adjusts the light amount of the light source unit 105 so as to compensate for the difference between the frame average brightness and the scene average brightness. At time t5, since the frame average brightness A2 is higher than the scene average brightness B1, the light source unit 105 is controlled to increase the amount of light. In FIG. 8, the amount of light E1 is at time t2, but increases to the amount of light E2 at time t3.

In the period from time t0 to time t3, which is a dark scene, the amount of light after dimming by the dimming unit 106 is a low value and changes for each frame as shown in FIG. On the other hand, the light intensity control value during the period from time t0 to time t3 is constant at C1 as shown in FIG. During the period from time t4 to time t8, which is a bright scene, the amount of light after being dimmed by the dimming unit 106 is a high value and changes for each frame as shown in FIG. On the other hand, the light intensity control value during the period from time t4 to time t8 is constant at C2 as shown in FIG. That is, the change in the light amount control value is smaller than the change in the frame average brightness. Therefore, the number of times the drive motor is driven can be suppressed when the amount of light is adjusted according to the input image data. Further, at time t4 in FIG. 5, the average frame brightness changes significantly and a scene change occurs, but in FIG. 7, the light amount control value greatly changes (at time t4) according to the timing of the scene change. Therefore, since the light amount control value is controlled quickly at the time of the scene change, it is possible to reduce the discomfort of the displayed image at the time of the scene change.

101 image signal input unit, 102 frame brightness detection unit, 103 scene brightness detection unit,
104 light amount control unit, 105 light source unit, 106 dimming unit, 107 correction amount control unit,
108 image signal correction unit, 109 display panel unit, 110 projection lens unit

Claims (3)

An image display device that controls the amount of light according to an image signal.
A scene brightness detector that detects scene brightness information that indicates the brightness of a scene consisting of multiple image frames,
A dimming unit that dims the amount of light from the light source by controlling a light-shielding member that blocks the amount of light from the light source.
It has a light amount control unit that controls the dimming amount of the dimming unit.
The scene luminance information detected by the scene luminance detection unit changes less frequently than the change in the signal level of the image signal.
The light amount control unit is an image display device characterized in that the dimming amount is controlled based on the scene brightness information detected by the scene brightness detection unit. An image display device that controls the amount of light according to an image signal.
An image detector that detects luminance information indicating the brightness of image data from the signal level of the image signal,
A scene brightness detection unit that determines a change in the scene from the brightness information detected by the image detection unit and detects the brightness information after the scene change as the scene brightness information.
A dimming unit that dims the amount of light from the light source by controlling a light-shielding member that blocks the amount of light from the light source.
It has a light amount control unit that controls the dimming amount of the dimming unit.
The scene luminance information detected by the scene luminance detection unit changes less frequently than the change in the signal level of the image signal.
The light amount control unit is an image display device characterized in that the dimming amount is controlled based on the scene brightness information detected by the scene brightness detection unit. An image display device that controls the amount of light according to an image signal.
An image detector that detects luminance information indicating the brightness of image data from the signal level of the image signal,
A scene brightness detector that detects scene brightness information that indicates the brightness of a scene consisting of multiple image frames,
A dimming unit that dims the amount of light from the light source by controlling a light-shielding member that blocks the amount of light from the light source.
It has a light amount control unit that controls the dimming amount of the dimming unit.
The scene brightness information detected by the scene brightness detection unit has a smaller number of changes than the change in the brightness information detected by the image detection unit.
The light amount control unit controls the dimming amount based on the scene brightness information detected by the scene brightness detection unit, and compensates for the difference between the scene brightness information detected by the scene brightness detection unit and the brightness information detected by the image detection unit. An image display device characterized by controlling the amount of light from a light source.